0 Assigned ID: 2650 ----- Attempting Submission 1 (Fri Dec 10 18:06:17 GMT 2021) ----- 0 ----- Attempting Submission 1 (Thu Dec 23 11:21:05 GMT 2021) ----- We ask for 3 WFC3/UVIS orbits to obtain F438W, F555W, and F814W images of the location of the Type Ia supernova (SN) 2017erp. We recently discovered a point source at the location of the SN in WFC3/IR observations taken during Feb. and Sep. 2021. We rule out the SN itself or a light echo. Instead, the object is consistent with a subgiant or red giant at a temperature of ~5000 K, but with an abnormally high luminosity of ~33,000 Solar luminosities. It may be a clump of red giants or a globular cluster at or behind the location of the SN. No other SN Ia has ever been directly associated with such a stellar group. A more exciting possibility is that this object is the shock-heated surviving companion of SN 2017erp's progenitor. If so, this will be the first-ever detection of a surviving companion in a normal SN Ia. It would also provide direct evidence of the "single degenerate" channel whereby a white dwarf explodes after accreting matter from a main sequence or evolved star. WFC3/UVIS has a higher resolution than WFC3/IR, which will allow us to precisely test the object's coincidence with the SN and determine whether it is resolved or not. The images will also flesh out the object's spectral energy distribution, for a more accurate classification, temperature, and luminosity. We ask for DD time so that these observations will be scheduled during 3-10 January 2022 or 14-28 February 2022, when one last infrared visit to this field is planned. By obtaining optical and infrared images at the same time, we will gain a complete snapshot of the object at a single moment in time, providing a baseline for comparison with any future observations to test the object's variability. The goal of this program is to obtain deep, clean images of the location of the Type Ia supernova 2017erp in F438W, F555W, and F814W. To that end, each orbit is devoted to one filter using a WFC3-UVIS-DITHER-BOX pattern. A critical aspect of this program is that it be carried out together with, or as close as possible to, vist 14 from program GO-16250 (the last visit to NGC 5861 in that program). That visit will provide F110W and F160W observations of the same location. We ask that our program be scheduled within +/- 2 days of GO-16250 visit 14 (the last visit to NGC 5861). Ideally, our program and GO-16250 visit 14 would be carried out together, as if they were one combined visit. Drs. Or Graur, Saurabh Jha, and Adam G. Riess are all expert supernova (SN) observers. Dr. Graur has used HST+WFC3 to lead several experiments similar to the one proposed here, with SN 2012cg (Graur et al. 2016), SN 2015F (Graur et al. 2018a), ASASSN-14lp (Graur et al. 2018b), SN 2014J (Graur 2019), and several SNe Ia in the near-infrared (Graur et al. 2020). Drs. Jha and Riess have a long record of observing SNe with HST. Dr. Wenlong Yuan is the PI of program GO-16250, which will provide the near-infrared data that will accompany the optical data requested here. Dr. Or Graur will serve as PI of this program and Dr. Saurabh Jha will serve as its US administrative Co-I. Stellar Physics and Stellar Types 0 false SUPPORTED EXT-STAR SUPERNOVA This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 The scheduling data was generated by CASM 29.2. CASM was run in Phase I mode. WFC3/UVIS Imaging No No F438W The scheduling data was generated by CASM 29.2. CASM was run in Phase I mode. WFC3/UVIS Imaging No No F555W The scheduling data was generated by CASM 29.2. CASM was run in Phase I mode. WFC3/UVIS Imaging No No F814W POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false 1640256971149 C:\Users\hkito\Documents\projects\telescope_proposals\HST\Cycle29\DD\OP-cache\sn17erp_DD_phaseII-v01.xml The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. 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